From dcae587b8cc9171dc23e08ec31f5b1720ed392e1 Mon Sep 17 00:00:00 2001
From: Maximilian Giller <m.giller.dev@gmail.com>
Date: Tue, 24 Jan 2023 20:23:16 +0100
Subject: [PATCH] Added light loss to refraction shader

---
 shader/refractionshader.cpp | 11 ++++++++---
 shader/refractionshader.h   |  3 ++-
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/shader/refractionshader.cpp b/shader/refractionshader.cpp
index e13916a..5312e30 100644
--- a/shader/refractionshader.cpp
+++ b/shader/refractionshader.cpp
@@ -1,8 +1,8 @@
 #include "scene/scene.h"
 #include "shader/refractionshader.h"
 
-RefractionShader::RefractionShader(float indexInside, float indexOutside, Color const &objectColor) : indexInside(
-        indexInside), indexOutside(indexOutside), objectColor(objectColor)
+RefractionShader::RefractionShader(float indexInside, float indexOutside, Color const &objectColor, float lightLoss) : indexInside(
+        indexInside), indexOutside(indexOutside), objectColor(objectColor), lightLoss(lightLoss)
 {}
 
 Color RefractionShader::shade(Scene const &scene, Ray const &ray) const
@@ -51,7 +51,12 @@ Color RefractionShader::shade(Scene const &scene, Ray const &ray) const
         }
 
         // Send out a new refracted ray into the scene
-        return scene.traceRay(refractionRay) * objectColor;
+        Color hitColor = scene.traceRay(refractionRay);
+
+        // Calculate light lost
+        float lightRemaining = 1;
+        if (refractionRay.primitive == ray.primitive) lightRemaining = 1 - lightLoss + exp(-refractionRay.length / 10) * lightLoss;
+        return hitColor * objectColor * lightRemaining;
     }
     return Color(0.0f, 0.0f, 0.0f);
 }
diff --git a/shader/refractionshader.h b/shader/refractionshader.h
index 7b489da..1da09c0 100644
--- a/shader/refractionshader.h
+++ b/shader/refractionshader.h
@@ -8,7 +8,7 @@ class RefractionShader : public Shader
 
 public:
     // Constructor
-    RefractionShader(float indexInside, float indexOutside, Color const &objectColor = Color(1, 1, 1));
+    RefractionShader(float indexInside, float indexOutside, Color const &objectColor = Color(1, 1, 1), float lightLoss = 0);
 
     // Shader functions
     Color shade(Scene const &scene, Ray const &ray) const override;
@@ -18,6 +18,7 @@ public:
 private:
     float indexInside;
     float indexOutside;
+    float lightLoss;
     Color objectColor;
 };